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RE: MTS&Cost based Optimzer

From: Rachel Carmichael <carmichr_at_hotmail.com>
Date: Tue, 24 Apr 2001 10:34:04 -0700
Message-ID: <F001.002F0C7F.20010424101558@fatcity.com>

Well, I was on 7.3.4 at the time.. so stored outlines were not an option. I haven't used them since, as the 8i databases I have are all new and we coded for cost-based to begin with.

Rachel

>From: "Mark Leith" <mark_at_cool-tools.co.uk>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: RE: MTS&Cost based Optimzer
>Date: Tue, 24 Apr 2001 08:21:57 -0800
>
>Rachel
>
>I recently heard about something called a Stored Outline that supposedly
>can
>be used to lock the execution path that a query runs with. One of the uses
>of this was apparently to aid people moving from rule to cost based
>optimisation, where the rule execution path may be the better option to go
>down.
>
>Did/have you looked at these as an alternative to the hint? I am curious to
>see if anybody has used this option and what feedback they may have?
>
>Cheers
>
>Mark
>
>-----Original Message-----
>Carmichael
>Sent: Tuesday, April 24, 2001 02:16
>To: Multiple recipients of list ORACLE-L
>
>
>
>turning on cost-based is easy: set the optimizer_mode parameter to choose
>in your init.ora, stop and start your database and then analyze all your
>tables.
>
>HOWEVER (and this is a biggie) this will not automatically make all your
>queries run faster. You will need to examine each and every query to see if
>it needs to be rewritten to take advantage of CBO. In fact, sometimes there
>are queries that run faster in rule-based, and I have had to include hints
>in queries to force the optimizer to run rule.
>
> >From: Venkat_Kalepalli <Venkat_Kalepalli_at_satyam.com>
> >Reply-To: ORACLE-L_at_fatcity.com
> >To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> >Subject: MTS&Cost based Optimzer
> >Date: Tue, 24 Apr 2001 02:25:25 -0800
> >
> > > Hello folks!
> > >
> > > I am working in SUN solaris 5.6 with Oracle 8i. I want to implement
>MTS
> > > on the Oracle server. Next we are running with Rule based optimizer
>and
> > > we want to change to costbased optimizer.
> > >
> > > I want to know what are the advantages we get on this and what are the
> > > steps to implement this?
> > >
> > > Any help is grateful...
> > >
> > > Rgd
> > > Venkat
> > > DBA.
> > >
> > >
> > >
>
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>--
>Author: Rachel Carmichael
> INET: carmichr_at_hotmail.com
>
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>Author: Mark Leith
> INET: mark_at_cool-tools.co.uk
>
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-- 
Author: Rachel Carmichael
  INET: carmichr_at_hotmail.com

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Received on Tue Apr 24 2001 - 12:34:04 CDT

Original text of this message

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